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Suzanne R Thorpe - One of the best experts on this subject based on the ideXlab platform.

  • combination therapy with the Advanced Glycation end product cross link breaker alagebrium and angiotensin converting enzyme inhibitors in diabetes synergy or redundancy
    Endocrinology, 2007
    Co-Authors: Melinda T Coughlan, Suzanne R Thorpe, Mark E Cooper, Vicki Thallasbonke, Josefa Pete, David M Long, Anna Gasser, David C K Tong, Maryann Arnstein
    Abstract:

    Blockade of Advanced Glycation end product (AGE) accumulation with alagebrium with concomitant angiotensin converting enzyme inhibition was tested for effects on renal function and on other postulated mediators of diabetic renal disease including the renin-angiotensin system, AGEs, mitochondrial and cytosolic oxidative stress, and intracellular signaling molecules. Sprague Dawley rats were rendered diabetic with streptozocin and followed consecutively for 32 wk with nondiabetic controls. Groups were treated with ramipril (1 mg/kg·d; wk 0–32); alagebrium (10 mg/kg·d; wk 16–32); or a combination of both. Although individual treatments had significant effects on albuminuria, no further improvements were seen with combination therapy. Changes in urinary vascular endothelial growth factor excretion mirrored those seen in albuminuria. Diabetes was associated with suppression of circulating angiotensin II in the context of increased circulating and renal levels of the AGE, carboxymethyllysine. All treatments att...

  • the serum concentration of the Advanced Glycation end product ne carboxymethyl lysine is increased in uremia technical note
    Kidney International, 1997
    Co-Authors: Thorsten P Degenhardt, Sharanya Reddy, Suzanne R Thorpe, Linda Grass
    Abstract:

    Advanced Glycation end products (AGEs) such as pentosidine and N epsilon-(carboxymethyl)lysine (CML) have been traditionally quantified by HPLC or gas chromatography--mass spectrometry (GC/MS). Enzyme-linked immunosorbent assays (ELISA) have been introduced as a convenient alternative to simplify the detection and measurement of AGEs in proteins and tissues, but some of these studies are limited by the lack of information on the structure of the epitopes recognized by antibodies to AGE-proteins. In this work we demonstrate that an antibody used in a previous study, reporting increased levels of AGEs in patients with diabetes or on continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD), recognizes CML as its major epitope. We also show that there is a significant correlation between the concentration of AGEs in serum measured by ELISA and a GC/MS assay for CML in serum proteins. Both analyses yielded comparable results, with patients on CAPD and HD having about threefold higher AGE- or CML-concentrations in their serum. Our data suggest that ELISA assays for CML should be useful for the clinical measurement of AGEs in serum proteins.

  • the Advanced Glycation end product nepsilon carboxymethyl lysine is a product of both lipid peroxidation and glycoxidation reactions
    Journal of Biological Chemistry, 1996
    Co-Authors: Minxin Fu, John W Baynes, Jesus R Requena, Alicia J Jenkins, Timothy J Lyons, Suzanne R Thorpe
    Abstract:

    Abstract N-(Carboxymethyl)lysine (CML) is an Advanced Glycation end product formed on protein by combined nonenzymatic Glycation and oxidation (glycoxidation) reactions. We now report that CML is also formed during metal-catalyzed oxidation of polyunsaturated fatty acids in the presence of protein. During copper-catalyzed oxidation in vitro, the CML content of low density lipoprotein increased in concert with conjugated dienes but was independent of the presence of the Amadori compound, fructoselysine, on the protein. CML was also formed in a time-dependent manner in RNase incubated under aerobic conditions in phosphate buffer containing arachidonate or linoleate; only trace amounts of CML were formed from oleate. After 6 days of incubation the yield of CML in RNase from arachidonate was 0.7 mmol/mol lysine compared with only 0.03 mmol/mol lysine for protein incubated under the same conditions with glucose. Glyoxal, a known precursor of CML, was also formed during incubation of RNase with arachidonate. These results suggest that lipid peroxidation, as well as glycoxidation, may be an important source of CML in tissue proteins in vivo and that CML may be a general marker of oxidative stress and long term damage to protein in aging, atherosclerosis, and diabetes.

  • the Advanced Glycation end product nepsilon carboxymethyl lysine is a product of both lipid peroxidation and glycoxidation reactions
    Journal of Biological Chemistry, 1996
    Co-Authors: Jesus R Requena, John W Baynes, Alicia J Jenkins, Timothy J Lyons, Suzanne R Thorpe
    Abstract:

    Nepsilon-(Carboxymethyl)lysine (CML) is an Advanced Glycation end product formed on protein by combined nonenzymatic Glycation and oxidation (glycoxidation) reactions. We now report that CML is also formed during metal-catalyzed oxidation of polyunsaturated fatty acids in the presence of protein. During copper-catalyzed oxidation in vitro, the CML content of low density lipoprotein increased in concert with conjugated dienes but was independent of the presence of the Amadori compound, fructoselysine, on the protein. CML was also formed in a time-dependent manner in RNase incubated under aerobic conditions in phosphate buffer containing arachidonate or linoleate; only trace amounts of CML were formed from oleate. After 6 days of incubation the yield of CML in RNase from arachidonate was approximately 0.7 mmol/mol lysine compared with only 0.03 mmol/mol lysine for protein incubated under the same conditions with glucose. Glyoxal, a known precursor of CML, was also formed during incubation of RNase with arachidonate. These results suggest that lipid peroxidation, as well as glycoxidation, may be an important source of CML in tissue proteins in vivo and that CML may be a general marker of oxidative stress and long term damage to protein in aging, atherosclerosis, and diabetes.

  • n epsilon carboxymethyl lysine is a dominant Advanced Glycation end product age antigen in tissue proteins
    Biochemistry, 1995
    Co-Authors: Sharanya Reddy, Johann Bichler, Kevin J Wellsknecht, Suzanne R Thorpe, John W Baynes
    Abstract:

    Advanced Glycation end products (AGEs) and glycoxidation products are formed during Maillard or browning reactions between sugars and proteins and are implicated in the pathophysiology of aging and the complications of diabetes. To determine the structure of AGEs, antibodies were prepared to protein browned by incubation with glucose and used in ELISA assays to measure AGEs formed in model reactions between bovine serum albumin (BSA) or N alpha-acetyllysine and glucose, fructose, or glyoxal. AGEs were formed from glucose and fructose only under oxidative conditions, but from glyoxal under both oxidative and antioxidative conditions. Gel permeation chromatographic analysis indicated that a similar AGE was formed in reactions of N alpha-acetyllysine with glucose, fructose, and glyoxal and that this AGE co-eluted with authentic N alpha-acetyl-N epsilon-(carboxymethyl)lysine. Amino acid analysis of AGE proteins revealed a significant content of N epsilon-(carboxymethyl)lysine (CML). In ELISA assays using polyclonal antibodies against AGE proteins, CML-BSA (approximately 25 mol of CML/mol of BSA), prepared by chemical modification of BSA, was a potent inhibitor of the recognition of AGE proteins and of AGEs in human lens proteins. We conclude that AGEs are largely glycoxidation products and that CML is a major AGE recognized in tissue proteins by polyclonal antibodies to AGE proteins.

Renbin Huang - One of the best experts on this subject based on the ideXlab platform.

  • effect of 2 dodecyl 6 methoxycyclohexa 2 5 diene 1 4 dione isolated from averrhoa carambola l oxalidaceae roots on Advanced Glycation end product mediated renal injury in type 2 diabetic kkay mice
    Toxicology Letters, 2013
    Co-Authors: Ni Zheng, Xing Lin, Qingwei Wen, Shijun Zhang, Jianchun Huang, Renbin Huang
    Abstract:

    Abstract The roots of Averrhoa carambola L. (Oxalidaceae) have a long history of medical use in traditional Chinese medicine for treating diabetes and diabetic nephropathy. 2-Dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione (DMDD) was isolated from the tuberous roots of A. carambola L. The purpose of this study was to investigate the beneficial effect of DMDD on the Advanced Glycation End-Product-mediated renal injury in type 2 diabetic KKAy mice with regard to prove its efficacy by local traditional practitioners in the treatment of kidney frailties in diabetics. KKAy mice were orally administrated DMDD (12.5, 25, 50 mg/kg body weight/d) or aminoguanidine (200 mg/kg body weight/d) for 8 weeks. Hyperglycemia, renal AGE formation, and the expression of related proteins, such as the AGE receptor, nuclear factor-κB, transforming growth factor-β1, and Ne-(carboxymethyl)lysine, were markedly decreased by DMDD. Diabetes-dependent alterations in proteinuria, serum creatinine, creatinine clearance, and serum urea-N and glomerular mesangial matrix expansion were attenuated after treatment with DMDD for 8 weeks. The activities of superoxide dismutase and glutathione peroxidase, which are reduced in the kidneys of KKAy mice, were enhanced by DMDD. These findings suggest that DMDD may inhibit the progression of diabetic nephropathy and may be a therapeutic agent for regulating several pharmacological targets to treat or prevent of diabetic nephropathy.

  • effect of 2 dodecyl 6 methoxycyclohexa 2 5 diene 1 4 dione isolated from averrhoa carambola l oxalidaceae roots on Advanced Glycation end product mediated renal injury in type 2 diabetic kkay mice
    Toxicology Letters, 2013
    Co-Authors: Ni Zheng, Xing Lin, Qingwei Wen, Shijun Zhang, Jianchun Huang, Renbin Huang
    Abstract:

    The roots of Averrhoa carambola L. (Oxalidaceae) have a long history of medical use in traditional Chinese medicine for treating diabetes and diabetic nephropathy. 2-dodecyl-6-methoxycyclohexa-2, 5-diene-1, 4-dione (DMDD) was isolated from the tuberous roots of Averrhoa carambola L. The purpose of this study was to investigate the beneficial effect of DMDD on the Advanced Glycation End-Product-mediated renal injury in type 2 diabetic KKAy mice with regard to prove its efficacy by local traditional practitioners in the treatment of kidney frailties in diabetics. KKAy mice were orally administrated DMDD (12.5, 25, 50 mg/kg body weight/d) or aminoguanidine (200 mg/kg body weight/d) for 8 weeks. Hyperglycemia, renal AGE formation, and the expression of related proteins, such as the AGE receptor, nuclear factor-κB, transforming growth factor-β1, and Ne-(carboxymethyl)lysine, were markedly decreased by DMDD. Diabetes-dependent alterations in proteinuria, serum creatinine, creatinine clearance, and serum urea-N and glomerular mesangial matrix expansion were attenuated after treatment with DMDD for 8 weeks. The activities of superoxide dismutase and glutathione peroxidase, which are reduced in the kidneys of KKAy mice, were enhanced by DMDD. These findings suggest that DMDD may inhibit the progression of diabetic nephropathy and may be a therapeutic agent for regulating several pharmacological targets to treat or prevent of diabetic nephropathy.

Shoichi Yamagishi - One of the best experts on this subject based on the ideXlab platform.

  • glucagon like peptide 1 suppresses Advanced Glycation end product induced monocyte chemoattractant protein 1 expression in mesangial cells by reducing Advanced Glycation end product receptor level
    Metabolism-clinical and Experimental, 2011
    Co-Authors: Yuji Ishibashi, Yuri Nishino, Takanori Matsui, Masayoshi Takeuchi, Shoichi Yamagishi
    Abstract:

    Advanced Glycation end products (AGE) and receptor for AGE (RAGE) interaction elicits reactive oxygen species (ROS) generation and inflammatory reactions, thereby being involved in the development and progression of diabetic nephropathy. Recently, we, along with others, found that glucagon-like peptide–1 (GLP-1), one of the incretins and a gut hormone secreted from L cells in the intestine in response to food intake, could have anti-inflammatory and antithrombogenic properties in cultured endothelial cells. However, the effects of GLP-1 on renal mesangial cells are largely unknown. Therefore, to elucidate the role of GLP-1 in diabetic nephropathy, this study investigated whether and how GLP-1 blocked AGE-induced monocyte chemoattractant protein–1 expression in human cultured mesangial cells. Gene and protein expression was analyzed by quantitative real-time reverse transcription polymerase chain reactions, Western blots, and enzyme-linked immunosorbent assay. The ROS generation was measured with dihydroethidium staining. Glucagon-like peptide–1 receptor (GLP-1R) was expressed in mesangial cells. Glucagon-like peptide–1 inhibited RAGE gene expression in mesangial cells, which was blocked by small interfering RNAs raised against GLP-1R. Furthermore, GLP-1 decreased ROS generation and subsequently reduced monocyte chemoattractant protein–1 gene and protein expression in AGE-exposed mesangial cells. An analogue of cyclic adenosine monophosphate mimicked the effects of GLP-1 on mesangial cells. Our present study suggests that GLP-1 may directly act on mesangial cells via GLP-1R and that it could work as an anti-inflammatory agent against AGE by reducing RAGE expression via activation of cyclic adenosine monophosphate pathway.

  • vildagliptin blocks vascular injury in thoracic aorta of diabetic rats by suppressing Advanced Glycation end product receptor axis
    Pharmacological Research, 2011
    Co-Authors: Takanori Matsui, Yuri Nishino, Masayoshi Takeuchi, Shoichi Yamagishi
    Abstract:

    Vildagliptin is a stable inhibitor of dipeptidyl peptidase-IV, a responsible enzyme that mainly inactivates glucagon-like peptide-1, and now one of the widely used agents for the treatment of diabetes. However, effects of vildagliptin on vascular injury in diabetes are largely unknown. Since Advanced Glycation end products (AGEs) and their receptor RAGE axis are reported to contribute to vascular complications in diabetes, we investigated here whether vildagliptin inhibits vascular damage in thoracic aorta of Otsuka Long-Evans Tokushima Fatty rats (OLETF rats), an animal model of type 2 diabetes with obesity, by blocking the AGEs-RAGE axis. OLETF and control LETO rats at 22 weeks old were given vehicle or 3 mg/kg of vildagliptin for another 12 weeks. Vildagliptin treatment decreased fasting plasma glucose and heart rate in OLETF rats. Compared with control LETO rats, levels of AGEs, RAGE mRNA and protein, an oxidative stress marker, 8-hydroxydeoxyguanosine, two membrane components of NADPH oxidase, p22 and gp91phox mRNAs, and phospho-NF-κB p65 in thoracic aorta were significantly enhanced in OLETF rats, all of which were inhibited by the treatment with vildagliptin. Vildagliptin significantly reduced both mRNA and protein levels of monocyte chemoattractant protein-1, vascular cell adhesion molecule-1 and plasminogen activator inhibitor-1 in thoracic aorta of OLETF rats. Enhanced expression of transforming growth factor-β in the aorta of diabetic rats was also suppressed by vildagliptin. Our present data suggest that vildagliptin could play a protective role against vascular injury in diabetes partly by attenuating the deleterious effects of AGEs-RAGE-oxidative stress axis.

  • pigment epithelium derived factor inhibits Advanced Glycation end product elicited mesangial cell damage by blocking nf κb activation
    Microvascular Research, 2010
    Co-Authors: Takanori Matsui, Yuji Ishibashi, Masayoshi Takeuchi, Shoichi Yamagishi
    Abstract:

    Abstract Advanced Glycation end products (AGE), senescent macroprotein derivatives formed at an accelerated rate under hyperglycemic conditions, elicit oxidative stress generation and inflammatory reactions, thus being involved in the development and progression of diabetic nephropathy. Recently, we, along with others, have found that pigment epithelium-derived factor (PEDF), a glycoprotein with potent neuronal differentiating activity, inhibits AGE-elicited endothelial cell damage through its anti-oxidative properties and blocks the progression of experimental diabetic retinopathy. However, a role of PEDF in diabetic nephropathy is not fully understood. In this study, we investigated whether and how PEDF could protect against AGE-elicited mesangial cell damage in vitro . PEDF mRNA and protein levels were decreased by the treatments of AGE. PEDF or neutralizing antibody raised against RAGE (receptor for AGE) was found to inhibit the AGE-induced oxidative stress generation and subsequent NF-κB activation in mesangial cells. Further, AGE increased mRNA levels of monocyte chemoattractant protein-1 (MCP-1), vascular cell adhesion molecule-1 (VCAM-1) and plasminogen activator inhibitor-1 (PAI-1) in mesangial cells, all of which were prevented by the treatments with PEDF, RAGE antibody or pyrrolidine dithiocarbamate, a NF-κB inhibitor. The present results demonstrated for the first time that PEDF blocked the AGE–RAGE-mediated mesangial cell injury by inhibiting NF-κB activation via suppression of reactive oxygen species generation. Our present study suggests that substitution of PEDF proteins may be a promising strategy for the treatment of diabetic nephropathy.

  • agents that block Advanced Glycation end product age rage receptor for ages oxidative stress system a novel therapeutic strategy for diabetic vascular complications
    Expert Opinion on Investigational Drugs, 2008
    Co-Authors: Shoichi Yamagishi, Takanori Matsui, Kazuo Nakamura, Seiji Ueda, Kei Fukami, Seiya Okuda
    Abstract:

    Background: Diabetic vascular complications are leading causes of acquired blindness, end-stage renal failure, a variety of neuropathies, and accelerated atherosclerosis, which together could account for disabilities and high mortality rates in patients with diabetes. Since there is accumulating evidence that the Advanced Glycation end product (AGE)–RAGE (receptor for AGEs)–oxidative stress axis is involved in diabetic vascular complications, inhibition of the AGE–RAGE system may be a promising target for therapeutic intervention in these devastating disorders. Objective: In this review, we discuss several types of agent that may be able to inhibit the AGE–RAGE–oxidative stress system, and their therapeutic implications in vascular complications in diabetes. Methods: We have analyzed currently available scientific literature in the field of AGE–RAGE to create a comprehensive review on novel therapeutic agents for vascular complications in diabetes. Results/conclusion: Inhibition of AGE formation, blockade...

  • pigment epithelium derived factor inhibits Advanced Glycation end product induced retinal vascular hyperpermeability by blocking reactive oxygen species mediated vascular endothelial growth factor expression
    Journal of Biological Chemistry, 2006
    Co-Authors: Shoichi Yamagishi, Takanori Matsui, Kazuo Nakamura, Yosuke Inagaki, Katsuhiko Takenaka, Yuko Jinnouchi, Yumiko Yoshida, Tetsuro Matsuura, Isao Narama, Yoshihiro Motomiya
    Abstract:

    Abstract Pigment epithelium-derived factor (PEDF) is the most potent inhibitor of angiogenesis, suggesting that loss of PEDF contributes to proliferative diabetic retinopathy. However, the role of PEDF against retinal vascular hyperpermeability remains to be elucidated. We investigated here whether and how PEDF could inhibit the Advanced Glycation end product (AGE) signaling to vascular hyperpermeability. Intravenous administration of AGEs to normal rats not only increased retinal vascular permeability by stimulating vascular endothelial growth factor (VEGF) expression but also decreased retinal PEDF levels. Simultaneous treatments with PEDF inhibited the AGE-elicited VEGF-mediated permeability by down-regulating mRNA levels of p22phox and gp91phox, membrane components of NADPH oxidase, and subsequently decreasing retinal levels of an oxidative stress marker, 8-hydroxydeoxyguanosine. PEDF also inhibited the AGE-induced vascular hyperpermeability evaluated by transendothelial electrical resistance by suppressing VEGF expression. Furthermore, PEDF decreased reactive oxygen species (ROS) generation in AGE-exposed endothelial cells by suppressing NADPH oxidase activity via down-regulation of mRNA levels of p22PHOX and gp91PHOX. This led to blockade of the AGE-elicited Ras activation and NF-κB-dependent VEGF gene induction in endothelial cells. These results indicate that the central mechanism for PEDF inhibition of the AGE signaling to vascular permeability is by suppression of NADPH oxidase-mediated ROS generation and subsequent VEGF expression. Substitution of PEDF may offer a promising strategy for halting the development of diabetic retinopathy.

Ni Zheng - One of the best experts on this subject based on the ideXlab platform.

  • effect of 2 dodecyl 6 methoxycyclohexa 2 5 diene 1 4 dione isolated from averrhoa carambola l oxalidaceae roots on Advanced Glycation end product mediated renal injury in type 2 diabetic kkay mice
    Toxicology Letters, 2013
    Co-Authors: Ni Zheng, Xing Lin, Qingwei Wen, Shijun Zhang, Jianchun Huang, Renbin Huang
    Abstract:

    Abstract The roots of Averrhoa carambola L. (Oxalidaceae) have a long history of medical use in traditional Chinese medicine for treating diabetes and diabetic nephropathy. 2-Dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione (DMDD) was isolated from the tuberous roots of A. carambola L. The purpose of this study was to investigate the beneficial effect of DMDD on the Advanced Glycation End-Product-mediated renal injury in type 2 diabetic KKAy mice with regard to prove its efficacy by local traditional practitioners in the treatment of kidney frailties in diabetics. KKAy mice were orally administrated DMDD (12.5, 25, 50 mg/kg body weight/d) or aminoguanidine (200 mg/kg body weight/d) for 8 weeks. Hyperglycemia, renal AGE formation, and the expression of related proteins, such as the AGE receptor, nuclear factor-κB, transforming growth factor-β1, and Ne-(carboxymethyl)lysine, were markedly decreased by DMDD. Diabetes-dependent alterations in proteinuria, serum creatinine, creatinine clearance, and serum urea-N and glomerular mesangial matrix expansion were attenuated after treatment with DMDD for 8 weeks. The activities of superoxide dismutase and glutathione peroxidase, which are reduced in the kidneys of KKAy mice, were enhanced by DMDD. These findings suggest that DMDD may inhibit the progression of diabetic nephropathy and may be a therapeutic agent for regulating several pharmacological targets to treat or prevent of diabetic nephropathy.

  • effect of 2 dodecyl 6 methoxycyclohexa 2 5 diene 1 4 dione isolated from averrhoa carambola l oxalidaceae roots on Advanced Glycation end product mediated renal injury in type 2 diabetic kkay mice
    Toxicology Letters, 2013
    Co-Authors: Ni Zheng, Xing Lin, Qingwei Wen, Shijun Zhang, Jianchun Huang, Renbin Huang
    Abstract:

    The roots of Averrhoa carambola L. (Oxalidaceae) have a long history of medical use in traditional Chinese medicine for treating diabetes and diabetic nephropathy. 2-dodecyl-6-methoxycyclohexa-2, 5-diene-1, 4-dione (DMDD) was isolated from the tuberous roots of Averrhoa carambola L. The purpose of this study was to investigate the beneficial effect of DMDD on the Advanced Glycation End-Product-mediated renal injury in type 2 diabetic KKAy mice with regard to prove its efficacy by local traditional practitioners in the treatment of kidney frailties in diabetics. KKAy mice were orally administrated DMDD (12.5, 25, 50 mg/kg body weight/d) or aminoguanidine (200 mg/kg body weight/d) for 8 weeks. Hyperglycemia, renal AGE formation, and the expression of related proteins, such as the AGE receptor, nuclear factor-κB, transforming growth factor-β1, and Ne-(carboxymethyl)lysine, were markedly decreased by DMDD. Diabetes-dependent alterations in proteinuria, serum creatinine, creatinine clearance, and serum urea-N and glomerular mesangial matrix expansion were attenuated after treatment with DMDD for 8 weeks. The activities of superoxide dismutase and glutathione peroxidase, which are reduced in the kidneys of KKAy mice, were enhanced by DMDD. These findings suggest that DMDD may inhibit the progression of diabetic nephropathy and may be a therapeutic agent for regulating several pharmacological targets to treat or prevent of diabetic nephropathy.

John W Baynes - One of the best experts on this subject based on the ideXlab platform.

  • chelation a fundamental mechanism of action of age inhibitors age breakers and other inhibitors of diabetes complications
    Diabetes, 2012
    Co-Authors: Ryoji Nagai, David B Murray, Thomas O Metz, John W Baynes
    Abstract:

    This article outlines evidence that Advanced Glycation end product (AGE) inhibitors and breakers act primarily as chelators, inhibiting metal-catalyzed oxidation reactions that catalyze AGE formation. We then present evidence that chelation is the most likely mechanism by which ACE inhibitors, angiotensin receptor blockers, and aldose reductase inhibitors inhibit AGE formation in diabetes. Finally, we note several recent studies demonstrating therapeutic benefits of chelators for diabetic cardiovascular and renal disease. We conclude that chronic, low-dose chelation therapy deserves serious consideration as a clinical tool for prevention and treatment of diabetes complications.

  • the Advanced Glycation end product nepsilon carboxymethyl lysine is a product of both lipid peroxidation and glycoxidation reactions
    Journal of Biological Chemistry, 1996
    Co-Authors: Jesus R Requena, John W Baynes, Alicia J Jenkins, Timothy J Lyons, Suzanne R Thorpe
    Abstract:

    Nepsilon-(Carboxymethyl)lysine (CML) is an Advanced Glycation end product formed on protein by combined nonenzymatic Glycation and oxidation (glycoxidation) reactions. We now report that CML is also formed during metal-catalyzed oxidation of polyunsaturated fatty acids in the presence of protein. During copper-catalyzed oxidation in vitro, the CML content of low density lipoprotein increased in concert with conjugated dienes but was independent of the presence of the Amadori compound, fructoselysine, on the protein. CML was also formed in a time-dependent manner in RNase incubated under aerobic conditions in phosphate buffer containing arachidonate or linoleate; only trace amounts of CML were formed from oleate. After 6 days of incubation the yield of CML in RNase from arachidonate was approximately 0.7 mmol/mol lysine compared with only 0.03 mmol/mol lysine for protein incubated under the same conditions with glucose. Glyoxal, a known precursor of CML, was also formed during incubation of RNase with arachidonate. These results suggest that lipid peroxidation, as well as glycoxidation, may be an important source of CML in tissue proteins in vivo and that CML may be a general marker of oxidative stress and long term damage to protein in aging, atherosclerosis, and diabetes.

  • the Advanced Glycation end product nepsilon carboxymethyl lysine is a product of both lipid peroxidation and glycoxidation reactions
    Journal of Biological Chemistry, 1996
    Co-Authors: Minxin Fu, John W Baynes, Jesus R Requena, Alicia J Jenkins, Timothy J Lyons, Suzanne R Thorpe
    Abstract:

    Abstract N-(Carboxymethyl)lysine (CML) is an Advanced Glycation end product formed on protein by combined nonenzymatic Glycation and oxidation (glycoxidation) reactions. We now report that CML is also formed during metal-catalyzed oxidation of polyunsaturated fatty acids in the presence of protein. During copper-catalyzed oxidation in vitro, the CML content of low density lipoprotein increased in concert with conjugated dienes but was independent of the presence of the Amadori compound, fructoselysine, on the protein. CML was also formed in a time-dependent manner in RNase incubated under aerobic conditions in phosphate buffer containing arachidonate or linoleate; only trace amounts of CML were formed from oleate. After 6 days of incubation the yield of CML in RNase from arachidonate was 0.7 mmol/mol lysine compared with only 0.03 mmol/mol lysine for protein incubated under the same conditions with glucose. Glyoxal, a known precursor of CML, was also formed during incubation of RNase with arachidonate. These results suggest that lipid peroxidation, as well as glycoxidation, may be an important source of CML in tissue proteins in vivo and that CML may be a general marker of oxidative stress and long term damage to protein in aging, atherosclerosis, and diabetes.

  • n epsilon carboxymethyl lysine is a dominant Advanced Glycation end product age antigen in tissue proteins
    Biochemistry, 1995
    Co-Authors: Sharanya Reddy, Johann Bichler, Kevin J Wellsknecht, Suzanne R Thorpe, John W Baynes
    Abstract:

    Advanced Glycation end products (AGEs) and glycoxidation products are formed during Maillard or browning reactions between sugars and proteins and are implicated in the pathophysiology of aging and the complications of diabetes. To determine the structure of AGEs, antibodies were prepared to protein browned by incubation with glucose and used in ELISA assays to measure AGEs formed in model reactions between bovine serum albumin (BSA) or N alpha-acetyllysine and glucose, fructose, or glyoxal. AGEs were formed from glucose and fructose only under oxidative conditions, but from glyoxal under both oxidative and antioxidative conditions. Gel permeation chromatographic analysis indicated that a similar AGE was formed in reactions of N alpha-acetyllysine with glucose, fructose, and glyoxal and that this AGE co-eluted with authentic N alpha-acetyl-N epsilon-(carboxymethyl)lysine. Amino acid analysis of AGE proteins revealed a significant content of N epsilon-(carboxymethyl)lysine (CML). In ELISA assays using polyclonal antibodies against AGE proteins, CML-BSA (approximately 25 mol of CML/mol of BSA), prepared by chemical modification of BSA, was a potent inhibitor of the recognition of AGE proteins and of AGEs in human lens proteins. We conclude that AGEs are largely glycoxidation products and that CML is a major AGE recognized in tissue proteins by polyclonal antibodies to AGE proteins.